JPH06470B2 - Travel transmission structure of agricultural tractor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has an engine and a main clutch case directly connected to the rear surface of the engine at the front of the machine body, and receives the output from the main clutch mechanism to provide the rear wheels and A transmission case that outputs to the front wheels is arranged in the rear part of the machine body, and a front wheel transmission that can switch between a standard drive state in which the front wheels are driven at approximately the same speed as the rear wheels and a high-speed drive state in which the front wheels are driven at a higher speed than the rear wheels. The present invention relates to a traveling transmission structure of an agricultural tractor interposed in a transmission system from a mission case to front wheels.

[Conventional technology]

In the traveling transmission structure of this type of agricultural tractor, in order to arrange the front wheel transmission, it has been conventionally provided at the lower front end of the transmission case arranged at the rear of the machine body (Japanese Patent Laid-Open No. 62-5).
5226 publication).

[Problems to be solved by the invention]

Therefore, this front wheel transmission is located on the rear side of the machine body, and the center of gravity of the traveling machine body is biased to the rear side,
By connecting a working device such as a cultivator to the rear end of the machine body, the balance weight at the front end of the machine body becomes heavier because the tendency to be in the rear center of gravity is further promoted.

An object of the present invention is to dispose the front wheel transmission in a state where the rear center of gravity of the vehicle can be eliminated as much as possible, and to easily change the specification vehicle equipped with the front wheel transmission and the specification vehicle not equipped with the front wheel transmission at the manufacturing stage. Is in the point of providing.

[Means for solving problems]

The characteristic configuration according to the present invention is that the front wheel transmission storage case is directly connected to the rear surface of the main clutch case in which the steering gear box is arranged in the vicinity, and the front wheel transmission is switched between the standard drive state and the high speed drive state by the operation of the pitman arm. The front wheel shifting operation mechanism is attached to a lid member that is detachable from the storage case. The operation and effect thereof are as follows.

[Work]

(A) Due to the characteristic configuration, the front wheel transmission is stored in the case connected to the rear surface of the main clutch case, so its mounting position is on the front side of the machine body, and the center of gravity position of the entire traveling machine body is adjusted. It can be moved forward compared to when it is attached to the front end of the mission case.

(B) From the perspective of merely shifting the center of gravity to the front side, it is possible to position the front wheel transmission in the front axle case, but the original specifications for agricultural tractors are that the left and right traveling devices are the front and rear axles of the machine. Since it is mounted on the traveling machine body for rolling operation around it, a complex linkage mechanism such as a universal join is used to link the front wheel transmission operation mechanism provided on the front axle case and the pitman arm mounted on the traveling machine body side. However, in the case of the present invention, since the positional relationship between the pitman arm and the front wheel transmission is fixed, and the two are arranged close to each other, a simple linkage plate is provided as a linkage mechanism. Etc.

(C) Moreover, because of the characteristic configuration, the operation mechanism for the front wheel transmission is detachable with respect to the storage case together with the lid member.Therefore, when manufacturing a specification vehicle equipped with the front wheel transmission and a specification vehicle not equipped with the front wheel transmission, The case for housing the front wheel transmission can be shared, and the specification can be easily changed by distinguishing only the lid member for front wheel shifting and the one without it. In this case, it is up to the manufacturer to install the front wheel transmission in the storage case for the specification vehicle not equipped with the front wheel transmission.

〔The invention's effect〕

Because of the action (a), the center of gravity can be moved to the front side, so that the balance weight provided at the front end of the machine body can be reduced in weight or eliminated. Therefore, the overall weight can be reduced, and the body frame structure and the like can be simplified.

From the action (b), by simplifying the linkage mechanism between the pitman arm and the front wheel transmission operation mechanism, the operation of the operation mechanism itself accurately reflects the operation of the pitman arm, and the steering wheel turning angle (40 ° or more) In this case, the operation timing can be ensured for the front wheel transmission of this type in which the front wheels need to be switched to the high speed drive state, and the reliability of the front wheel transmission is enhanced.

Due to the action (c), even if the specifications are different, it is possible to provide a product suitable for the user's needs because the specifications can be easily changed and the parts can be commonly used.

〔Example〕

As shown in FIG. 6, an engine (1), a radiator (2), a steering operation part (4) provided with a steering handle (3) behind it, a mission case (5) and a mission case (5) behind it. It is equipped with a link mechanism (6) that connects the tiller etc. so that it can be moved up and down.
By arranging (7) and (8), a four-wheel drive agricultural tractor is constructed.

The arrangement configuration of the front wheel transmission (9) described below will be described. As shown in FIG. 1, a storage case (11) in which a main clutch case (10) is directly connected to the rear surface of the engine (1) and a front wheel transmission (9) is mounted on the rear surface of the main clutch case (10). Are connected and fixed. A steering gear box (13) pivotally supporting a handle operating shaft (12) is fixed to the upper surface of the storage case (11). Next, the transmission system from the main clutch to the front wheel transmission (9) will be described. As shown in FIG. 2, the output shaft (15) provided with the main clutch mechanism (14) is connected to the main clutch case (10). It is projected and supported in the storage case (11), and the output shaft is placed in the storage case (11).
A first transmission shaft (17) located below (15) and transmitting power to the input shaft (16) on the mission case (5) side, and further below the first transmission shaft (17) receiving front wheel driving force from the mission case (5) The second transmission shaft (18), and the third transmission shaft (19), one end of which is relatively rotatably fitted and held with the inner end of the second transmission shaft (18) aligned with the axial center. The fourth transmission shafts (21) to the front axle case (20) are provided below the three transmission shafts (19), respectively. The output shaft (15) has a first gear (22) and a first transmission shaft (17)
The second gear (23) is attached to the first gear through this gear transmission mechanism.
Power transmission to the transmission shaft (17) and the first transmission shaft (17)
The power transmitted to the mission case (5) is transmitted to the second transmission shaft (18) as front wheel driving force. On the other hand, the first transmission shaft
A relay transmission member (26) integrally formed with a pair of large and small third gear (24) and fourth gear (25) is loosely fitted in (17), and a friction multi-plate hydraulic clutch is attached to the third transmission shaft (19). The mechanism (27) is provided, and the inner end of the second transmission shaft (18) is formed integrally with the fifth gear (28). Here, the hydraulic clutch mechanism (27) is the third clutch.
A hydraulic clutch case (30) formed with a sixth gear (29) that constantly meshes with the gear (24), and a rotating member (31) that cooperates with the hydraulic clutch case (30) to support the friction plate. And a clutch sleeve (33) provided with an internal gear (18A) of the second transmission shaft (18) and an external gear capable of engaging and disengaging freely at the other end of the piston (32) which acts on the friction plate at one end. Has been done. Furthermore, the front end of the third transmission shaft (19) and the rear end of the fourth transmission shaft (21) are each provided with a seventh
The gear (34) and the eighth gear (35) are spline-fitted to each other, and
A transmission structure is formed on the transmission shaft (21).

Therefore, when the clutch sleeve (33) is engaged with the internal gear (18A) of the second transmission shaft (18), the power transmitted to the second transmission shaft (18) is transmitted through the clutch sleeve (33) to the first position. 3 transmission shafts
It is transmitted to (19) and the standard drive state in which the front wheels (7) and the rear wheels (8) are driven at substantially the same speed is revealed, and the clutch sleeve (33) is operated to the opposite side to operate the hydraulic clutch mechanism ( The power transmitted to the second transmission shaft (18) when the second transmission shaft (18) is operated is transmitted through the relay transmission member (26) and the clutch case (30) to the third transmission shaft.
It is transmitted to (19) and the high speed driving state in which the front wheels (7) are driven at high speed with respect to the rear wheels (8) is revealed.

The operation mechanism for the front wheel transmission (9) as described above will be described in detail. As shown in FIGS. 3 to 5, this operating mechanism is
(49) is a bolt on the side surface of the storage case (11).
It is equipped in a mounting case as a lid member (36) configured to be detachable with (50).

This operation mechanism has a horizontal operation shaft with respect to the mounting case (36).
A pitman arm (38) and an operating shaft (37) that pivotally support (37) and are also pivotally supported by the steering gear box (13).
A link plate (40) as a mechanical linking mechanism is connected to the operation arm (39) fixed to the above, and the hydraulic clutch mechanism (27) is operated by a steering operation. A support holder (41) is supported at the inner end of the operation shaft (37) in a state in which the operation shaft (37) is allowed to rotate, and the support holder (41) and the mounting case (36) are also supported.
The sliding rod (42) is installed between the inner wall surface and the sliding rod (42), and the axial center of the operating shaft (37) is orthogonal to the axial center (X).
It is configured to be slidable in the (Y) direction. The sliding rod (4
A rotating roller (44) is attached to one end of 2) via a supporting member (43), and is rotatable integrally with the operating shaft (37) and slidable in the axial center (X) direction. Cam plate (45)
Is fitted over the spline. The cam plate (45) acts on the rotary roller (44) by the rotation of the cam plate (45) about the axis (X), so that the sliding rod (42) moves in the axis (Y) direction. A cam surface composed of a small-diameter circular hole portion (45b) and a large-diameter circular hole portion (45a) that move forward and backward is formed. A shift fork (46) acting on the clutch sleeve (33) of the front wheel transmission (9) is fitted to an end of the sliding rod (42) opposite to the support member (43). , This shift fork (46) has a support holder (41) and a shift fork
A first spring (47) interposed between (46) and a second spring (47) interposed between the sliding rod (42) and the shift fork (46).
It is neutrally urged by the spring (48), and its movement is restricted by the contact between the cam plate (45) and the rotating roller (44). Then, as shown in FIG. 4, when the steering operation amount is equal to or less than a predetermined amount (rotation angle is 40 ° or less), the small diameter circular hole portion (45b) of the cam plate (45) serves as the rotation roller (44). The shift fork (46) is located on the right side in the drawing with the rotating roller (44) and the small diameter circular hole (45b) separated from each other, and the clutch sleeve (3
3) is engaged with the internal gear (18A) to expose the front wheel standard drive state. From this standard drive state, when the pitman arm (38) is rocked by the steering operation, one of the two large-diameter circular hole portions (45a) acts on the rotating roller (44) and the sliding rod (42) is opposed. Direction, and actuate the hydraulic clutch mechanism (27) to expose the high speed drive state. The cam plate (45) is equipped with a shift fork (49), and the cam plate (45) is moved in the axial center (X) direction of the operation shaft (37) to correspond to the rotating roller (44). When retracted from the position, the cam plate (45) does not move the sliding rod (42) even if the steering operation is performed, and the shift fork (49) constitutes a mechanism for restricting the high speed drive state.

[Another embodiment]

The front wheel shifting operation mechanism (49) may take other forms.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

The drawings show an embodiment of a traveling transmission structure for an agricultural tractor according to the present invention, FIG. 1 is a side view showing an installation position of a front wheel transmission, and FIG. 2 is a longitudinal side view showing a transmission structure of a front wheel transmission. 3 is a cross-sectional plan view showing the gear shifting operation structure of the front wheel transmission, FIG. 4 is a vertical sectional side view showing the gear shifting operation structure of the front wheel transmission, and FIG. 5 is a longitudinal rear view showing the gear shifting operation structure of the front wheel transmission. FIG. 6 is a side view of the agricultural tractor. (1) …… Engine, (5) …… Mission Case, (7) ……
Front wheel, (8) …… Rear wheel, (9) …… Front wheel transmission, (10) …… Main clutch case, (11) …… Storage case, (13) …… Steering gear box, (14) …… Main clutch mechanism, (36) ...
... Lid member, (38) ... Pitman arm, (49) ... Front wheel shifting operation mechanism.

Claims (1)

[Claims] 1. An engine (1) and a main clutch case (10) directly connected to the rear surface of the engine (1) are arranged in the front part of the machine body, and the rear wheels () receive the output from the main clutch mechanism (14). 8) and the transmission case (5) that outputs to the front wheels (7) are arranged in the rear part of the fuselage, and the front wheels (7) and the rear wheels (8) are driven at approximately the same speed as the standard driving state and the rear wheels (8). ) A front wheel transmission (9) that can be switched to a high-speed driving state that drives at a higher speed is installed in the transmission system of the agricultural tractor, which is installed in the transmission system from the transmission case (5) to the front wheels (7). Therefore, while directly connecting the front wheel transmission (9) and the storage case (11) to the rear surface of the main clutch case (10) with the steering gear box (13) arranged in the vicinity,
A front wheel shifting operation mechanism (49) for switching the front wheel transmission (9) between a standard driving state and a high speed driving state by operating a pitman arm (38), which is detachable from the storage case (11). Traveling transmission structure for agricultural tractors attached to (36).